// Setup
const collection = {
  "2548": {
    "album": "Slippery When Wet",
    "artist": "Bon Jovi",
    "tracks": [
      "Let It Rock",
      "You Give Love a Bad Name"
    ]
  },
  "2468": {
    "album": "1999",
    "artist": "Prince",
    "tracks": [
      "1999",
      "Little Red Corvette"
    ]
  },
  "1245": {
    "artist": "Robert Palmer",
    "tracks": []
  },
  "5439": {
    "album": "ABBA Gold"
  }
};
// Keep a copy of the collection for tests
const collectionCopy = JSON.parse( JSON.stringify( collection ) );

// Only change code below this line
function updateRecords( id, prop, value ) {
  //if prop != "tracks" and value !== null, id[prop] = value
  if ( prop !== "tracks" && value !== "" ) {
    collection[ id ][ prop ] = value;
  } else
    //if prop === "tracks" and id.hasOwnProperty(tracks) == false, create tracks = [], then tracks.push(value)
    if ( prop === "tracks" && collection[ id ].hasOwnProperty( "tracks" ) === false ) {
      const tracks = collection[ id ][ "tracks" ] = [];
      tracks.push( value );
    } else
      //if prop === "tracks" and value != null, tracks.push(value)
      if ( prop === "tracks" && collection[ id ].hasOwnProperty( "tracks" ) && value !== "" ) {
        collection[ id ][ "tracks" ].push( value );
      } else
        //if value == null, delete prop from id
        if ( value === "" ) {
          delete collection[ id ][ prop ];
        }

  return collection;
}

// Alter values below to test your code
console.log( updateRecords( 2548, "tracks", "" ) );
